<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>浮动原理</title>
<style>
	#box1{ width:150px; height:150px; background:red; }
	#box2{ width:50px; height:50px; background:green; float:left; }
	#box3{ width:80px; height:80px; background:blue; clear:left; }
</style>
</head>
<body>
<div id="box1">
	<div id="box2"></div>
    <div id="box3"></div>	
</div>
</body>
</body>
</html>




